Combination lock



Oct. 16, 1956 WHITEHEAD COMBINATION LOCK 2 Sheecs-Sheet 1 Filed June 4, 1953 WHITEHEA D F. WHlTEHEAD COMBINATION LOCK Oct.

2 Sheets-Sheet 2 Filed June 4, 1955 IE all? flm'rvg MHz/7540 W M 7% I United States Patent 6 COMBINATION LOCK Frank Whitehead, Liverpool, England, assignor to Milners Safe Company Limited, Liverpool, England, a British company Application June 4, 1953, Serial No. 359,461

Claims priority, application Great Britain June 6, 1952 13 Claims. (Cl. 70-133) The present invention relates to permutation locks, commonly referred to as combination locks, which embody an operating element which may consist of a lever (which will hereinafter be referred to as the lever), pivoted to a bolt, and which is displaceable to open the lock when it is allowed to engage a driver element, usually in the form of a driver wheel or disc. As a rule, a projection on the lever is adapted to engage in a gate on the driver wheel, and a fence on the lever is adapted to engage in gates in a series of tumblers, so that when the gates of the tumblers are aligned with the fence and the gate of the driver wheel is aligned with the projection, the lever can move to allow the fence and projection to engage in the gates of the tumblers and driver wheel respectively to enable the lock to be opened.

In most locks of this kind, a projection of the lever rides on the driver wheel to hold the fence out of contact with the tumblers, but with this kind of lock it is possible for an unauthorised person to determine the relationship between the gate of the driver wheel and the dial of the lock by feeling, and by subsequent manipulation of the dial it is possible to ascertain the relationship between the dial and one or more of the gates of the tumblers.

According to one feature of the present invention a lock of the type set forth is provided with; a guard element adapted to hold the lever in a position in which the fence is out of contact with the tumblers, but which is movable in a given direction to release the lever, and adapted, when so moved, to lock the driver wheel, and thus the dial, against angular rotation.

According to a further feature of the present invention a permutation or combination lock including tumblers, a driving wheel for adjusting the tumblers and for actuating the bolt, and a lever pivotally connected to the bolt and having a fence co-operating with the tumblers and a portion co-operating with the driver wheel, is characterised by the provision of a guard element which is adapted to hold the lever in a position in which the fence and the portion co-operating with the driver wheel are out of contact with the tumblers and the driver wheel respectively but which is movable in a given direction to release the lever and is adapted when so moved to lock the driver wheel against angular rotation.

In a preferred arrangement, this guard consists of a circular disc, of a diameter not less than that of the driver wheel, angularly fixed relatively to the driver wheel so as to rotate therewith, and adapted at its periphery to engage the lever or a part secured thereto, but to be axially displaced, under the control of a plunger passing centrally through the dial, to move its periphery out of engagement with the lever. The said disc has a pin projecting axially therefrom adapted to abut against the casing of the lock so as normally to prevent the disc from such axial displacement. The casing is provided with one or more apertures therein to receive the pin so as to permit such axial displacement, and one of said apertures must be appropriately placed so as to receive the pin at ice a position of the disc at which the gate of the driving wheel is aligned with the projection of the lever.

Before further describing the invention reference will be made to the manner in which a lock may be sensed or felt by an unauthorised person. The gate in the driver wheel is generally of a fishhook shape so that on rotation of the driver wheel in one direction the hook portion of one side of the gate can pull the lever to withdraw the bolt, whilst the other side of the gate is in contrast almost convex in shape and merges with the outer circumference of the driver wheel so that, in co-operation with a fixed stop, rotation of the driver wheel in the opposite direction first causes the lever to extend the bolt and then causes the projection of the lever to be disengaged from the gate of the driver wheel at the same time causing the fence to be lifted out of the gates in the tumblers.

When the combination is dispersed, that is to say, when at least one of the tumblers is in a position with its gate out of alignment with the fence, the projection on the lever normally rides on the periphery of the driver wheel, but when the gate in the driver wheel is beneath the projection on the lever the latter is no longer supported by the driver wheel and consequently the fence comes into contact with the periphery of one or more of the tumblers. If now the driver wheel is rocked slightly in either direction by manipulation of the dial, it is possible to detect points on the dial at which the projection on the lever comes into contact with the sides of the gate in the driver wheel. The extent of such rotation of the driver wheel as indicated by the dial will depend upon the distance between the projection on the lever and the centre of the driver wheel, and owing to manufacturing tolerances this distance is dependent to a large extent upon which tumbler the fence is resting. Accordingly by careful manipulation of the driver wheel it is possible to detect slight changes in the extent through which the driver wheel may be rotated and by carefully noting these deviations in relation to dial markings to which the dial has been previously rotated, it is possible for such a combination lock to be sensed.

The present invention substantially locks the driver wheel against rotation when the guard element is moved to permit the lever to engage the driver wheel and thus obviates the possibility of sensing such a lock by the method described.

In one embodiment of the invention there is provided adjacent to the driver wheel, rotatable therewith and axially displaceable away therefrom by operation of a manual control, a disc member having a diameter not less than that of the driver wheel having a cut-away portion of the same general shape as the gate in the driver wheel together with an associated closure member resiliently urged into a closed position so that the disc normally presents a substantially continuous circumferential surface. The closure member is cut away to provide, when in its closed position, a recess to receive a pin extending in an axial direction from the outer edge of the projection of the lever. A stop pin projects in an axial direction from the disc but displaced from its axis and co-operates with an aperture in the casing of the lock. When the disc is adjacent to the driver wheel the pin on the disc is clear of the aperture and both the driver wheel and disc are free to rotate whilst the pin on the projection of the lever rides on the circumference of the disc and/ or driver wheel. The aperture in the casing is so located that axial displacement of the disc away from the driver wheel is prevented by the pin on the disc except when the disc and driver wheel are in such positions that the gate in the driver wheel is beneath the projection of the lever, and

- displacement of the disc then permits the lever to move towards the centre of the driver wheel so that the projection of the lever is received within the gate of the driver wheel if the gates of the tumblers are in registry with the fence. When the disc is displaced the stop pin on the disc enters the aperture in the casing of the lock to prevent rotation of the driver wheel and disc. On return of the disc to its normal position the pin on the projection of the lever is received in the space defined by the recess in the disc and the closure member and the stop pin is brought out of engagement with the aperture in the casing of the lock to permit further rotation of the driver wheel in one direction for withdrawal of the bolt. Subsequent rotation of the driver wheel in the opposition direction causes the bolt to be extended and further rotation causes displacement of the closure member, to enable the projection on the lever to be moved out of engagement with the gate on the driver wheel.

The invention will be further described by way of example with reference to the accompanying drawings in which:

Fig. 1 is an exploded perspective view of one embodiment of the invention,

Fig. 2 is a rear elevation of the embodiment shown in Fig. 1, i. e. looking in the direction of the arrow A in Fig. l, with the casing removed,

Fig. 3 gives detailed views of the driver wheel, disc and closure,

Fig. 4 is a vertical section along the line 4-4 in Fig. 3 with the disc adjacent to the driver wheel, and

Fig. 5 is a detailed view corresponding to Fig. 4 when the disc is in its displaced position.

Fig. 6 is a fragmentary view of the driver wheel, disc and closure drawn to an enlarged scale.

In the drawings only such parts of the lock as enable the present invention to be understood are shown. Referring more particularly to views 1 and 2, a combination lock comprises a base plate 10 adapted to be fitted to the rear or inside surface of a door or the like and a cover plate 11 secured to the base plate by means of screws not shown. Afiixed to the front surface of the door is an escutcheon plate not shown, adjacent to which is a dial 12 attached to a knurled knob 13, secured to a shaft 14 which extends through the door and through a boss 15 attached to the base plate 10. The boss 15 carries a number of tumblers 16, of which there are three in the embodiment shown. A bolt 17, slidably mounted in a guide 18 attached to base plate 10, carries a lever 19 pivoted about screw 20' and urged towards the centre of the boss and tumblers by spring 21. The lever 19 carries a projection 22 extending towards the centre of the tumblers and a fence 23 which extends transversely across the peripheral surfaces of the tumblers 16. Each of the tumblers 16 has a cut-away portion or gate 24 to receive the fence. A stop member 25 upstanding from the base plate 19 co-operates with an inclined surface 26 on the fence 23 to prevent withdrawal of the fence from the gates in the tumblers except when the bolt is in its extended or locking position. The outer end of the stop 25 is rectangular shaped as at 27 and is received in a correspondingly shaped opening 28 in the casing 11.

The shaft 14 extends through the boss 15 and is screwed to receive a driver wheel 29, both the internal bore of the driver wheel 29 and the shaft 14 being grooved to receive a key 30, the shaft 14 being threaded primarily to allow for adjustment in accordance with the thickness of the door. The driver Wheel 29 has a notch or cut-away portion known as a gate 31, which is hook-shaped and will be seen more clearly in Fig. 3, to receive the projection 22 of the lever 19.

Shaft 14 is bored to receive a rod 32 which extends therethrough and is threaded at its inner end to receive disc 33, the outer end having affixed thereto a press-button 34. The shaft 14 is counterbored to receive a compression spring and the knurled knob 13 is preferably counter- 4 bored to a largre diameter to receive the button 34. Disc 33 is centrally drilled and tapped as at 33a and is received on the inner end of rod 32 and retained thereon by means of a lock nut 35. Disc 33 has a generally hook-shaped portion cut away as at 36 and is adapted to rotate in fixed relationship with the driver wheel 29 by means of pins 37 received in bores 38 in disc 33. A second disc 39 also rotatable with driver wheel 29 is drilled at 49 to receive pins 37 and is attached to disc 33 by means of screws 41,. which pass through countersunk holes 42 and are received in threaded holes 43 in disc 33. A closure member 44 is slidably mounted on disc 39 by pin and slot connections 45 and 46, and is urged into its closed position by a spring 47. The disc 33, the disc 39 and the closure member 44 form in combination a guard disc. Referring more particularly to Fig. 3, the closure position of the closure member 44 is indicated by the broken line completing the circumference of the disc 33, from which it will be seen that when the member 44 is in the closed position, the cutaway portion 36 of the disc 33 and the member 44 define a space 48 as indicated in Fig. 3 and in Fig. 2. The disc 39 also carries, at a point displaced from the centre of the disc, at rearwardly projecting stop pin 49 which co-operates with an aperture 50 formed in the back plate of the casing 11. The space 48 is adapted to receive, as will be subsequently described, a pin 51, which projects rearwardly from the projection 22 on the lever 19.

The interrelationship between the driver wheel 29, the disc 33, the disc 39, the projection 22 and the pin 51 is more clearly indicated in Fig. 6. The disc 39 is slightly greater in diameter than the driver wheel 29 by for example one thirty-second of an inch and the disc 33 is bevelled to accommodate the major part of the difference in diameter of the disc 39 and the driver wheel 29. The pin 51 adjoins the outer edge of the projection 22 and tapers slightly outwardly to conform to the bevel of the disc 33.

The disc 39 is attached to the disc 33 which is carried on rod 32 and the discs are by spring 34a urged into their normal position which is with disc 33 in face-to-face contact with driver wheel 29. In these conditions the pin 51, extending from the projection 22 of the lever 19 normally rides on the circumference of the disc 33 and the outer edge of the projection 22 is raised slightly off the driver wheel 29, as may be seen most clearly in Fig. 6.

The operation of the lock will now be described, commencing from the conditions in which the bolt is extended and the combination dispersed. The embodiment shown contains three tumblers 16 and may be adjusted in known manner by means of locks 55 accessible through a keyhole 56 in the rear casing and a setting mark on the escutcheon (not shown) for a single, double or treble cipher combination. Depending on the combination set the knob 13 is rotated appropriately in a well known manner, successively anti-clockwise and clockwise to bring about rotation of the tumblers 16 by means of a pin 52 which projects forwardly from the driver wheel 29 and co-operates with element 53. For example, if the dial 12 were graduated in divisions and the lock were adjusted for the combination 20, 40, 80, the knob 13 would be rotated through at least three revolutions in an anticlockwise direction until the cipher 20 on the dial 12 came adjacent a mark on the escutcheon, then the knob would be rotated in a clockwise direction until the cipher 40 came adjacent the mark for the third time. The knob would. then be rotated in an anticlockwise direction until I the third cipher of the combination, 80, came adjacent the mark for the second time. By these rotations the gates in the tumblers would be brought into alignment beneath the fence 23; the knob 13 must now be rotated in a clockwise direction, i. e. in the opposite direction to the immediately preceding direction of rotation, to bring the recess in the driver wheel 29 beneath the projection 22:

on the lever 19. This position may correspond to any particular number on the dial, for example 10,. being adjacent to the mark on the escutcheon.

The stop pin 49 on the disc 39 and the aperture 50 in the rear casing 11 are so positioned in relation to one another and to the gate in the driver wheel 29 that when the gate 31 in the driver wheel 29 is beneath the projection 22 of the lever 19, the stop pin 49 is substantially co-axial with the aperture 50. Under these conditions the parts are in the relative dispositions one to another as shown in Fig. 4. If now the button 34 is depressed rod 32 moves inwardly and carries discs 33 and 39 away from face-to-face contact with driver wheel 29, bringing stop pin 49 into engagement with aperture 50 and enabling the pin 51 on the projection 22 from lever 19 to come out of engagement with the peripheral surface of the closure 44, thereby permitting the projection 22 to fall into the gate 31 of the driver wheel 29. The inter-arrangement of the discs 33, 39, stop pin 49 and driver wheel 29, when the discs are displaced therefrom is indicated in Fig. 5, in which for the sake of clarity, the pin 51 and the projection 22 of the lever 19 are not shown. It will, however, be appreciated that when the button 34 is pressed, stop pin 49 engages aperture 50 and substantially prevents rotation of the knob 13, shaft 14, driver wheel 29 and discs 33 and 39, thereby obviating any sensing of the lock.

The lock, however, cannot be further operated to withdraw the bolt 17 with the button 34 depressed, and this must, therefore, be released to bring stop pin 49 out of engagement with aperture 50 and permit further operation of the driver wheel 29. On release of pin 34 the discs 33 and 39 are returned to bring disc 33 into face-to-face contact with driver wheel 29 and the pin 51 is received in the space 43 defined by the closure member 44 and the recess 36 in disc 33; this is indicated most clearly in Fig. 2. R- tation of the knob 13 in an anticlockwise direction as seen in Fig. 2, that is to say, in a clockwise direction as seen from the front of the lock, causes lever 19 to withdraw bolt 17.

When it is required to extend the bolt into the locking position, the knob 13 is turned in a clockwise direction as seen in Fig. 2 and pin 51 is brought into contact with one end of closure member 44, and since stop member 25 prevents the fence 23 from being brought out of the gates of the tumblers, lever 19 is caused to travel to the right as seen in Fig. 2 and move the bolt 17 into the locking position. Further rotation of the knob 13 causes the closure member 44 to be displaced into the position indicated by the broken line in Fig. 2 and causes lever 19 to pivot in a clockwise direction about the pivot 20, so that fence 23 is raised out of the gates on the tumblers 16 by the projection 22 moving along the inclined face 54 of the gate on the driver wheel 29. When the projection 22 has been raised sufiiciently far for the pin 51 to clear the closure member 44, the latter is restored into its closed position by the spring 47 so that the fence 23 is kept clear of the tumblers 16 and the projection 22 is kept clear of the gate in the driver wheel 29 by the pin 51 sliding over the substantially continuous peripheral surface presented by the disc 33 and the closure 44.

I claim:

1. A permutation or combination lock having a plurality of tumbler wheels each having a gate in the periphery thereof, a bolt, a driver wheel for adjusting said tumbler wheels and for actuating said bolt and having a cut-out in the periphery thereof, a lever pivotally connected to said bolt for engagement with said cut-out, a fence on said lever adapted to enter the gates of said tumbler wheels when all said gates are in register therewith, said trunbler wheels blocking movement of said lever into engagement with said cut out except when they are shifted to predetermined set positions in register with said fence, a guard disc co-axial with said driver wheel and normally disposed adjacent said driver wheel, said guard disc having a hook-shaped recess in the periphery thereof and having a closure member for said-recess to provide a normally substantially continuous peripheral surface to said disc, a pin projecting from said lever axially of the driver wheel for engagement with said peripheral surface of said disc for holding said lever in a position in which said fence is out of engagement with the peripheries of said tumbler wheels, means for displacing said guard disc axially of said driver wheel away from said driver wheel to release said lever for movement into engagement with said cut-out when all said gates of said tumbler wheels are in register with said fence, said disc and said closure member defining a recess to receive said pin projecting from said lever when said lever is in engagement with said cut-out of said driver wheel, and so permit the return of said guard disc to its normal position when said lever is in engagement with said cut-out whereby further rotation of said driver wheel in one direction can withdraw said bolt, a fixed element extending transversely of the axis of said driver wheel and spaced from said driver wheel in the direction of displacement of said guard disc, a projection extending axially from said guard disc at a point offset from its centre, and co-operating with said fixed element to normally prevent displacement of said disc, said element having an aperture at a position in register with the position of said projection when said' cut-out is in register with said lever to permit displacement of said guard disc by receiving said projection in said aperture only when said cut-out is in register with said lever, and to prevent rotation of said driver wheel when said guard disc is displaced.

2. A permutation or combination lock having a plurality of tumbler wheels each having a gate in the periphery thereof, a belt, a driver wheel for adjusting said tumbler wheels and for actuating said bolt andrhaving a cut-out in the periphery thereof, a lever pivotally connected to said bolt for engagement with said cut-out of said driver wheel, a fence on said lever extending across the peripheries of said tumbler wheels and adapted to enter said gates of said tumbler wheels when all said gates are in register therewith, said tumbler wheels blocking movement of said lever into engagement with said out out except when they are shifted to predetermined se't positions in register with said fence, a guard disc co-axial with said driver wheel and having a diameter not less than the diameter of the driver wheel, said disc having a hookshaped recess formed in the periphery thereof and having a closure member for said recess to provide a normally substantially continuous peripheral surface to said disc, said closure member being movable relatively to said disc, resilient means to urge said closure member into a closing position, a pin projecting from said lever axially of the driver wheel for contacting the periphery of the guard disc, said guard disc being normally disposed adjacent said driver wheel for engaging said pin to hold said lever with said fence out of engagement with the peripheries of said tumbler wheels, manually operated means for displacing said guard disc axially of said driver wheel away from said driver wheel to disengage the periphery of said disc from said pin to release said lever for movement into engagement with said cut-out when all said gates of said tumbler wheels are in register with said fence, said disc and said closure member defining a recess to receive said pin projecting from said lever when said lever is in engagement with said cut-out of said driver wheel, and so permit the return of said guard disc to its normal position when said lever is in engagement with said cut-out whereby further rotation of said driver wheel in one direction can withdraw said bolt, movement of said closure member relatively to said disc on rotation of said driver wheel in the opposite direction subsequent to retraction of said bolt permitting said pin to emerge from said recess and said lever to disengage said cut-out of the driver wheel without displacement of the guard disc relatively to the driver wheel, means for preventing displacement of said guard disc except when said cut-out is in register with said lever, and means for preventing rotation of said driver Wheel when said guard disc is displaced.

3. A permutation or combination lock having'a plurality of tumbler wheels each having a gate in the periphery thereof, a bolt, 21 driver wheel for adjusting said tumbler wheel and for actuating said bolt and having a cut-out in the periphery thereof, a lever pivotally connected to said bolt for engagement with said cut-out, a fence on said lever adapted to enter the gates of said tumbler wheels when all said gates are in register therewith, said tumbler Wheels blocking movement of said lever into engagement with said out out except when they are shifted to predetermined set positions in register with said fence, a guard disc coaxial with said driver wheel and normally disposed adjacent said driver wheel, said disc having a hook-shaped recess formed in the periphery thereof and having a closure member for said recess to provide a normally substantially continuous peripheral surface to said disc, a pin projecting from said lever axially of the driver wheel for engagement with said peripheral surface of said disc, said closure member being movable relatively to said disc, resilient means to urge said closure member into a closing position for holding said lever with said fence out of engagement with the peripheries of the tumbler wheels, means for displacing said guard disc axially of said driver wheel away from said driver wheel to release said lever for movement into engagement with said cut-out when all said gates of said tumbler wheels are in register with said fence, said disc and said closure member defining a recess to receive said pin projecting from said lever when said lever is in engagement with said cut-out on said driver wheel, and so permit the return of said guard disc to its normal position when said lever is in engagement with said cut-out whereby further rotation of said driver wheel in one direction can withdraw said bolt, movement of said closure member relatively to saidd isc on rotation of said driver wheel in the opposite direction subsequent to retraction of said bolt permitting said pin to emerge from said recess and said lever to disengage said cut-out on the driver Wheel without displacement of the guard disc relatively to the driver wheel, a fixed element extending transversely of the axis of said driver wheel and spaced from said driver wheel in the direction of displacement of said guard disc, a projection extending axially from said guard disc at a point offset from its centre, and co-operating with said element to normally prevent displacement of said disc, said fixed element having an aperture at a position in register with the position of said projection when said cut-out is in register with said lever to permit displacement of said guard disc by receiving said projection in said aperture only when said cut-out is in register with said lever, and to prevent rotation of said driver wheel when said guard disc is displaced.

4. A permutation or combination lock having a plurality of tumbler wheels each having a gate in the periphery thereof, a bolt, a driver wheel for adjusting said tumbler wheels and for actuating said bolt, a drive shaft, said tumbler wheels being freely rotatable about the axis of said drive shaft, means for keying said driver wheel to one end of said drive shaft, a calibrated dial at the other end of said drive shaft to rotate therewith, said driver wheel having a cut-out in the periphery thereof, a lever pivotally connected to said bolt for engagement with said cut-out on said driver wheel, a fence associated with said lever extending across the peripheries of said tumbler wheels and adapted to enter said gates of said tumbler wheels when all said gates are in register therewith, said tumbler wheels blocking movement of said lever into engagement with said cut out except when they are shifted to predetermined set positions in register with said fence, guard means for holding said lever with said fence out of contact with the peripheries of said tumbler wheels, said drive shaft having a bore, a manually operable plunger element extending through said bore for displacing said guard means from a normal position to release said lever and said fence to permit said fence to contact the peripheries of said tumbler wheels and thereby permit said lever to engage the cutout of the driver wheel when said cut-out is in register therewith and when said tumbler wheels are in register with said fence, resilient means for urging said guard means into said normal position, means for preventing displacement of said guard means except when said cut-out of said driver wheel is in register with said lever and means for preventing rotation of said driver wheel when said guard means is displaced.

5. A permutation or combination lock having a plurality of tumbler wheels each having a gate in the periphery thereof, a bolt, a driver wheel for adjusting said tumbler wheels and for actuating said bolt, said driver wheel having a hook-shaped cut-out in the periphery thereof, a

" lever pivotally connected to said bolt for engagement with said hook-shaped cut-out, a fence on said lever adapted to enter said gates of said tumbler wheels when all said gates are in register therewith, said tumbler wheels blocking movement of said lever into engagement with said cut out except when they are shifted to predetermined set positions in register with said fence, a circular guard disc co-axial with and rotatable with said driver wheel for holding said lever in a position in which said fence is out of engagement with the peripheries of said tumbler wheels, means for displacing said guard disc axially of said driver wheel to release said lever for movement into engagement with said cut-out when all said gates of said tumbler wheels are in register with said fence, means for preventing displacement of said guard disc except when said cutout is in register with said lever, and means for preventing rotation of said driver wheel when said guard disc is displaced.

6. A permutation or combination lock having a plurality of tumbler wheels each having a gate in the periphery thereof, a bolt, a driver wheel for selectively adjusting said tumbler wheels and for actuating said bolt and having a cut-out in the periphery thereof, a lever pivotally connected to said bolt for engagement with said cut-out, a fence on said lever adapted to enter the gates of said tumbler wheels when all said gates are in register therewith, said tumbler wheels blocking movement of said lever into engagement with said cut out except when they are shifted to predetermined set positions in register with said fence, a guard disc co-axial with said driver wheel and normally disposed adjacent said driver wheel for holding said lever in a position in which said fence is out of engagement with the peripheries of the tumbler wheels by engagement between the periphery of said disc and said lever, means for displacing said guard disc axially of said driver wheel away from said driver wheel to release said lever to permit it to engage with said cut-out when all said gates on said tumbler wheels are in register with said fence, means for preventing displacement of said guard disc except when said cut-out is in register with said lever, and means for preventing rotation of said driver wheel when said guard disc is displaced.

7. A permutation or combination lock having a plurality of tumbler wheels each having a gate in the periphery thereof, a bolt, a driver wheel for adjusting said tumbler wheels and for actuating said bolt and having a cutout in the periphery thereof, a lever pivotally connected to said bolt for engagement with said cut-out, a fence on said lever adapted to enter the gates of said tumbler wheels when all said gates are in register therewith, said tumbler wheels blocking movement of said lever into engagement with said out out except when they are shifted to predetermined set positions in register with said fence, a guard disc co-axial with said driver wheel and normally disposed adjacent said driver wheel for holding said lever in a position in which said fence is out of engagement with the peripheries of said tumbler wheels by engagement between the periphery of said disc and said lever, means for displacing said guard disc axially of said driver wheel away from said driver wheel to release said lever for movement into engagement with said cut-out when all greases said gates of said tumbler wheels are in register with said fence, a fixed element extending transversely of the axis of said driver wheel and spaced from said driver wheel in the direction of displacement of said guard disc, a projection extending axially from said guard disc at a point offset from its centre and co-operating with said element to normally prevent displacement of said disc, said element having an aperture therein at a position in register with the position of said projection when said cut-out is in register with said lever to permit displacement of said guard disc by receiving said projection in said aperture only when said cut-out is in register with said lever, and to prevent rotation of said driver wheel when said guard disc is displaced.

8. A permutation or combination lock having a plurality of tumbler wheels each having a gate in the periphery thereof, a bolt, a driver wheel for adjusting said tumbler wheels and for actuating said bolt and having a cutout in the periphery thereof, a lever pivotally connected to said bolt for engagement with said cut-out, a fence on said lever adapted to enter the gates of said tumbler wheels when all said gates are in register therewith, said tumbler wheels blocking movement of said lever into engagement with said cut out except when they are shifted to predetermined set positions in register with said fence, a guard disc co-axial with said driver wheel and normally disposed adjacent said driver wheel, said guard disc having a hookshaped recess in the periphery thereof and having a closure member for said recess to provide a normally substantially continuous peripheral surface to said disc, a pin projecting from said lever axially of the driver wheel for engagement with said peripheral surface of said disc for holding said lever in a position in which said fence is out of engagement with the peripheries of said tumbler wheels by engagement between the periphery of said disc and said pin, means for displacing said guard disc axially of said driver wheel away from said driver wheel to release said lever for movement into engagement with said cut-out when all said gates on said tumbler wheels are in register with said fence, said disc and said closure member defining a recess to receive said pin projecting from said lever when said lever is in engagement with said cut-out of said driver wheel, and so permit the return of said guard disc to its normal position when said lever is in engagement with said cut-out whereby further rotation of said driver wheel in one direction can withdraw said bolt, means for preventing displacement of said guard disc except when said cut-out is in register with said lever, and means for preventing rotation of said driver wheel when said guard disc is displaced.

9. A permutation or combination lock having a plurality of tumbler wheels each having a gate in the periphery thereof, a bolt, a driver wheel for adjusting said tumbler wheels and for actuating said bolt and having a cut-out in the periphery thereof, a lever pivotally connected to said bolt for engagement with said cut-out, a fence on said lever adapted to enter the gates of said tumbler wheels when all said gates are in register therewith, said tumbler wheels blocking movement of said lever into engagement with said cut out except when they are shifted to predetermined set positions in register with said fence, a guard disc co-axial with said driver wheel and normally disposed adjacent said driver wheel, said guard disc having a hook-shaped recess in the periphery thereof and having a closure member for said recess to provide a normally substantially continuous peripheral surface to said disc, a pin projecting from said lever axially of the driver Wheel for engagement with said peripheral surface of said disc for holding said lever in a position in which said fence is out of engagement with the peripheries of said tumbler wheels and in which said lever is out of engagement with said driver wheel by engagement between the periphery of said disc and said pin, means for displacing said guard disc axially of said driver wheel away from said driver wheel to release said lever for movement into engagement with said cut-out when all said gates on said tumbler wheels are in register with said fence, said disc and said closure member defining a recess to receive said pin projecting from said lever when said lever is in engagement with said cut-out of said driver wheel, and so permit the return of said guard disc to its normal position when said lever is in engagement with said out out whereby further rotation of said driver wheel in one direct-ion can withdraw said bolt, means for preventing displacement of said guard disc except when said cut-out is in register with said lever, and means for preventing rotation of said driver Wheel when said guard disc is displaced.

10. A permutation or combination lock having a plurality of tumbler wheels each having a gate in the periphery thereof, a bolt, a driver wheel for adjusting said tumbler wheels and for actuating said bolt and having a cutout in the periphery thereof, a lever pivotally connected to said bolt for engagement with said cut-out of said driver wheel, a fence on said lever extending across the peripheries of said tumbler wheels and adapted to enter said gates of said tumbler wheels when all said gates are in register therewith, said tumbler wheels blocking movement of said lever into engagement with said cut out except when they are shifted top'redetermined set positions in register with said fence, a guard disc co-axial with said driver wheel and having a diameter not less than the diameter of the driver wheel, said guard disc having a hook-shaped recess formed in the periphery thereof and having a closure member for said recess to provide a normally substantially continuous peripheral surface to said disc, a pin projecting from said lever axially of the driver wheel for contacting the periphery of the guard disc, said guard disc being normally disposed adjacent said driver wheel for engaging said pin to hold said lever in a position in which said fence is out of engagement with said tumbler wheels, manually operated means for displacing said guard disc axially of said driver wheel away from said driver wheel to disengage the periphery of said disc with said pin to release said lever to permit it to come into engagement with said cut-out when all said gates of said tumbler wheels are in register with said fence, said disc and said closure member defining a recess to receive said pin projecting from said lever when said lever is in engagement with said cut-out of said driver wheel, and so permit the return of said guard disc to its normal position when said lever is in engagement with said cut-out whereby further rotation of said driver wheel in one direction can withdraw said bolt, means for preventing displacement of said guard disc except when said cut-out is in register With said lever, and means for preventing rotation of said driver Wheel when said guard disc is displaced.

11. In a combination lock of the kind having a movable locking member, a manually-rotatable dial shaft, a disc like cam secured to said shaft for rotation with said shaft, said cam having a gate in the periphery thereof, a movable lever associated with said locking member for controlling movement thereof, said lever having a projection and having a fence, said projection being formed to interlock with the gate of said cam when the latter is rotated to a predetermined position with respect to said projection, whereby continued rotation of said cam in one direction shifts said lever and said locking member to an unlocked position, the walls defining said gate being formed to move said projection and thereby said lever, to a position released from said cam when said cam is rotated in the opposite direction, a plurality of tumblers interconnected by lost motion driving connections and being operably mounted for rotation about the axis of said shaft, and a lost motion driving connection between said cam and one of said tumblers, said tumblers, through said fence, blocking movement of said projection from said released position except when they are shifted to predetermined set positions in which said 11 projection is permitted to move to a position interlocked with said earn; the improvement of which comprises a circular guard disc co-axial with and rotatable with said cam for holding said fence in a position spaced from the tumblers throughout the rotation of said cam which is required to move said tumblers to said set positions, manually operable means for displacing said guard disc axially of said cam to release said fence for movement into engagement with the tumblers, means for holding said shaft against rotation at the time of displacement of said guard disc, and means for preventing displacement of said guard disc except when said cam is in said predetermined position with respect to said projection.

12. In a combination lock of the kind having a movable locking member, a manually-rotatable dial shaft, a disc like cam secured to said shaft for rotation with said shaft, said cam having a gate in the periphery thereof, a movable lever associated with said locking member for controlling movement thereof, said lever having a projection and having a fence, said projection being formed to interlock with the gate of said cam when the latter is rotated to a predetermined position with respect to said projection, whereby continued rotation of said cam in one direction shifts said lever and said locking member to an unlocked position, the walls defining said gate being formed to move said projection, and thereby said lever, to a position released from said cam when said cam is rotated in the opposite direction, a plurality of tumblers interconnected by lost motion driving connections and being operably mounted for rotation about the axis of said shaft, and a lost motion driving con nection between said cam and one of said tumblers, said tumblers, through said fence, blocking movement of said projection from said released position except when they are shifted to predetermined set positions in which said projection is permitted to move to a position interlocked with said cam; the improvement of which com prises a circular guard disc co-axial with and rotatable with said cam for imparting continued movement to said lever, when said projection moves to said released position, to a position to which said projection and said fence are spaced from the cam and tumblers respectively and for continuously holding said lever in said position with said projection and said fence spaced from the cam and tumblers respectively throughout the rotation of said cam which is required to move said tumblers to said set position, manually operable means for displacing said guard disc axially of said cam to release said lever for movement of said fence into engagement with the tumblers and for movement of said projection into interlockin engagement with the gate of said cam if said tumblers are in said predetermined set position, means for holding said shaft against rotation at the time of displacement of said guard disc, and means for preventing displacement of said guard disc except when said cam is in said predetermined position with respect to said projection for interlocking engagement of said projection with the gate of said cam.

13. In a combination lock of the kind having a movable locking member, a manually-rotatable dial shaft, a disc like cam secured to said shaft for rotation with said shaft, said cam having a gate in the periphery thereof, a movable lever associated with said locking member for controlling movement thereof, said lever having a projection and having a fence, said projection being formed to interlock with the gate of said cam when the latter is rotated to a predetermined position with respect to said projection, whereby continued rotation of said cam in one direction shifts said lever and said locking member to an unlocked position, the walls defining said gate being formed to move said projection, and thereby said lever, to a position released from said cam when said cam is rotated in the opposite direction, a plurality of tumblers interconnected by lost motion driving connections and being operably mounted for rotation about the axis of said shaft, and a lost motion driving connection between said cam and one of said tumblers, said tumblers, through said fence, blocking movement of said projection from said released position except when they are shifted to predetermined set positions in which said projection is permitted to move to a position interlocked with said cam; the improvement of which comprises a pin extending axially of the cam and operatively connected to the projection, a circular guard disc co-axial with and rotatable with said cam and having a diameter slightly larger than said cam for co-operation with said pin for imparting continued movement to said proj'ec-j tron, when said lever moves to said released position,.

to a position in which said projection and said fenceare spaced from the cam and tumblers respectively and for continuously holding said lever in said position with said projection and said fence spaced from the cam and tumblers respectively throughout the rotation of said cam which is required to move said tumblers to said set positions, said guard disc having a hook-shaped recess in the periphery thereof and having a displaceable closure member for said recess to provide a normally substantially continuous peripheral surface to said guard disc, resilient means to urge said closure member into a closing position, said guard disc being normally disposed adjacent said cam, manually operable means for displacing said guard disc axially of said cam and away from said cam to disengage said pin from the periphery of said guard disc and so release said lever for movement of said fence into engagement with the tumblers and for movement of said projection into interlocking engagement with the gate of said cam if said tumblers are in said predetermined set positions, said guard disc and said closure member defining a recess to receive said pin when said projection is in interlocking engagement with the gate of said cam and so permit said guard disc to be returned to its normal position when said projection is interlocked with said gate whereby further rotation of said cam in one direction can withdraw said movable locking member, a projecting member extending axially from said guard disc at a point offset from its centre, a fixed element extending transversely of the axis of said cam and spaced from said cam in the direction of displacement of said guard disc, said fixed element having an aperture at a position in register with the position of said projecting member when the cam is in said predeermined position with respect to said projection for interlocking engagement of said projection with the gate of said cam whereby to permit displacement of the guard disc from its normal position by receiving said projecting member in said aperture substantially only when said cam is in said predetermined position and hold the shaft against rotation at the time of displacement of said guard 

